A hobber has been produced as an exemplary gear machining apparatus. The hobber is an apparatus for cutting a tooth profile with an involute curve on a workpiece using a hob. In the hobber, the workpiece is supported by a table while the hob is supported by a tool head. The hob and the workpiece are rotated at a constant relation by their corresponding drive mechanisms. Further, the hob is configured to be fed relatively to the workpiece along a gear shaft direction of the workpiece at a constant feeding amount by means of a feeder mechanism.
In a work machine including a bobber as described above, it has been demanded to set a cutting speed to be suitable for respective conditions in order to enhance a machining efficiency. For example, Japan Laid-open Patent Application Publication No. JP-A-2008-213097 describes a method of obtaining a cutting speed based on a hardness of a workpiece material. On the other hand, Japan Laid-open Patent Application Publication No. JP-A-2001-87945 describes a relation between a gear module and a cutting speed in a hobber (e.g., FIG. 17).